The influence of implant articular thickness and glenohumeral conformity on stability of an all-metal glenoid component.

The objective of this study was to determine the effect of implant thickness and glenohumeral conformity on fixation of an all-metal glenoid component. A stainless steel glenoid component was designed and implanted in 10 cadaveric scapulae. A testing apparatus capable of producing a loading vector at various angles, magnitudes, and directions was used. The independent variables included 6 directions and 3 angles of joint load, 3 implant thicknesses, and 4 glenohumeral conformities. Implant micromotion relative to bone was measured by use of 4 displacement transducers at the superior, inferior, anterior, and posterior sites. The components displayed a consistent response to loading of ipsilateral compression and contralateral distraction. Stability decreased as the load application angle increased (P < .05). A decrease in the implant thickness and glenohumeral conformity resulted in increased implant stability (P < .05). Decreasing implant thickness and glenohumeral conformity reduce the eccentric component of loading and may improve the durability of glenoid implants.

Glenoid vault endosteal dimensions: an anthropometric study with special interest in implant design.

An understanding of the morphology of the glenoid is important from the viewpoint of implant design and selection. This study describes the endosteal dimensions and shape of the glenoid and correlates these results with age, gender, and the presence of osteoarthritis. This study used 72 scapulae. Data were obtained from computed tomography scans of both cadaveric and in vivo glenoids. The glenoid is relatively straight-sided in the coronal plane and more highly fluted in the transverse plane. The endosteal dimensions were larger for male specimens, but there was no difference in endosteal shape with respect to gender. These findings were not influenced by age or the presence of osteoarthritis. This study suggests that traditional glenoid component designs may not be optimal. To maximize fixation, a rectangular keel may be most effective in the coronal plane and a triangular keel may be most effective in the transverse plane.

Outcome after open reduction and internal fixation of capitellar and trochlear fractures.

BACKGROUND: Capitellar and trochlear fractures are uncommon fractures of the distal aspect of the humerus. There is limited information about the functional outcome of patients managed with open reduction and internal fixation. METHODS: The functional outcome of twenty-eight patients, with a mean age (and standard deviation) of 43 +/- 13 years, who were treated with open reduction and internal fixation for capitellar and trochlear fractures was evaluated at a mean duration of follow-up of 56 +/- 33 months. Patient outcomes were assessed with physical and radiographic examination, range-of-motion measurements, strength testing, and self-reported questionnaires (Short Form-36, Mayo Elbow Performance Index, American Shoulder and Elbow Surgeons Elbow Assessment Form, and Patient-Rated Elbow Evaluation scales). RESULTS: Eleven fractures involved the capitellum with or without fracture of the lateral ridge of the trochlea, four involved the capitellum and trochlea as one piece, and thirteen involved the capitellum and trochlea as separate fragments. These fractures were further characterized by the presence or absence of posterior comminution. Fourteen patients had isolated fractures, and fourteen had other elbow, forearm, or wrist injuries. Patients with more complex fractures required more extensive surgery, had more complications resulting in secondary procedures, and had poorer outcomes compared with those with simple fractures. The average score on the Mayo Elbow Performance Index (91 +/- 11), the average quality-of-life scores (46 on the physical component and 50 on the mental component of the Short Form-36), and the average range of motion (19 degrees to 138 degrees ) suggest favorable patient outcomes overall. Two comminuted fractures did not unite and required conversion to a total elbow arthroplasty. CONCLUSIONS: Patients with isolated noncomminuted capitellar and/or trochlear fractures have better results than those with more complex fractures. A classification system based on the radiographic patterns of these fractures is recommended.

Quality-of-life outcome following hemiarthroplasty or total shoulder arthroplasty in patients with osteoarthritis. A prospective, randomized trial.

BACKGROUND: Both total shoulder arthroplasty and hemiarthroplasty have been used commonly to treat severe osteoarthritis of the shoulder; however, their effect on disease-specific quality-of-life outcome is unknown. The purpose of this study was to compare the quality-of-life outcome following hemiarthroplasty with that following total shoulder arthroplasty in patients with osteoarthritis of the shoulder. METHODS: Forty-two patients with a diagnosis of osteoarthritis of the shoulder were randomized to receive a hemiarthroplasty or a total shoulder arthroplasty. One patient died, and all others were evaluated preoperatively and at six weeks and three, six, twelve, eighteen, and twenty-four months postoperatively with use of a standardized format including a disease-specific quality-of-life measurement tool (Western Ontario Osteoarthritis of the Shoulder [WOOS] index), general shoulder rating scales (University of California at Los Angeles [UCLA] shoulder scale, Constant score, and American Shoulder and Elbow Surgeons [ASES] evaluation form), general pain scales (McGill pain score and visual analogue scale), and a global health measure (Short Form-36 [SF-36]). When a patient required revision of a hemiarthroplasty to a total shoulder arthroplasty, the last score before he or she "crossed over" was used for the analysis. RESULTS: Significant improvements in disease-specific quality of life were seen two years after both the total shoulder arthroplasties and the hemiarthroplasties. There were no significant differences in quality of life (WOOS score) between the group treated with total shoulder arthroplasty and that treated with hemiarthroplasty (90.6 +/- 13.2 and 81.5 +/- 24.1 points, respectively; p = 0.18). The other outcome measures demonstrated similar findings. Two patients in the hemiarthroplasty group crossed over to the other group by undergoing a revision to a total shoulder arthroplasty because of glenoid arthrosis. CONCLUSIONS: Both total shoulder arthroplasty and hemiarthroplasty improve disease-specific and general quality-of-life measurements. With the small number of patients in our study, we found no significant differences in these measurements between the two treatment groups. LEVEL OF EVIDENCE: Therapeutic Level I.

Internal fixation of radial neck fractures: an in vitro biomechanical analysis.

OBJECTIVE: To assess the fixation rigidities of a custom designed blade plate, a 2.7 mm T-plate and 3.0 mm cannulated screws. DESIGN: A cadaveric non-comminuted radial neck fracture model was employed to test the three fixation methods, using a multi-directional shear loading protocol. BACKGROUND: The management of displaced radial neck fractures in adults remains unsatisfactory due to failure of internal fixation with secondary loss of reduction, and non-unions. METHODS: The stiffness of the various fixation methods was measured in five directions of loading in the transverse plane. Failure testing was performed on the final testing condition for each specimen, in a posteroulnar to anteroradial direction. RESULTS: The direction of specimen loading did not have a significant effect on the stiffness of the various methods of fixation (P = 0.4). There was no significant difference in the fixation stiffness between the 3.0 mm screws or blade plate, however, both were superior to the T-plate (P < 0.05). CONCLUSIONS: Although the 2.7 mm T-plate has been reported in the literature as a viable method of fixation for radial neck fractures, it may not be optimal from the viewpoint of fixation stability. In the setting of a non-comminuted radial neck fracture, the use of cross-cannulated screws or blade plate fixation is preferred.Relevance This study supports the use of cross-cannulated screws or blade plate fixation for non-comminuted fractures of the radial neck.

Does keel size, the use of screws, and the use of bone cement affect fixation of a metal glenoid implant?

The objective of this study was to determine the effect of screws and keel size on the fixation of an all-metal glenoid component. A prototype stainless-steel glenoid component was designed and implanted in 10 cadaveric scapulae. A testing apparatus capable of producing a loading vector at various angles, magnitudes, and directions was used. The independent variables included six directions and three angles of joint load, and five fixation modalities-three different-sized cross-keels (small, medium, and large), screws, and bone cement. Implant micromotion relative to bone was measured by four displacement transducers at the superior, inferior, anterior, and posterior sites. The components displayed a consistent response to loading of ipsilateral compression and contralateral distraction. Use of progressively larger keels did not significantly improve implant stability. Stability decreased as the angle of load application increased (P <.05). Screw and cement fixation resulted in the most stable fixation (P <.05).

Distal biceps tendon repair: comparison of surgical techniques.

PURPOSE: Various surgical repair techniques for distal biceps tendon ruptures have been reported, however, the optimal technique is unknown. METHODS: Over a 4-year period 19 distal biceps tendon ruptures were repaired: 9 using a single anterior incision and 10 using a modified 2-incision Boyd and Anderson technique. The patients were followed-up prospectively and independently reviewed. RESULTS: Patient-rated elbow evaluation and Short Form-36 (SF-36) scores improved with time independent of surgical technique. At 1 year the 1-incision group regained more flexion (142.8 degrees vs 131.1 degrees ) than the 2-incision group. There was no difference between groups in supination motion, supination strength, or flexion strength, although recovery of flexion strength was initially more rapid for the 2-incision group. Complications were encountered in 44% of cases treated with a 1-incision technique and in 10% of cases treated with the 2-incision technique; however, most of these were minor transient paresthesias. CONCLUSIONS: The differences between the 2 groups were relatively minor with the Morrey 2-incision technique showing a slightly more rapid recovery of flexion strength and fewer complications as compared with the 1-incision technique.

Functional outcome of AO type C distal humeral fractures.

PURPOSE: To review the functional outcome of AO type C distal humeral fractures (bicondylar fractures) managed with dual orthogonal plate fixation. METHOD: Twenty-three patients were reviewed retrospectively at a mean of 45.1 months. Patient-rated outcomes (Disabilities of the Arm Shoulder and Hand [DASH], Patient Rated Ulnar Nerve Evaluation [PRUNE], American Shoulder and Elbow Surgeons Elbow form [ASES-e], and Short Form-36 [SF-36]), clinical, radiographic, and objective evaluations were used to assess outcomes. RESULTS: Almost 40% of patients required a third plate for adequate fixation. Patients identified minimal subjective deficits (10%) with a mean satisfaction of 93%. The arc of motion was decreased in the flexion-extension plane (122 degrees relative to 138 degrees, p <.01), whereas strength was lower for both elbow flexion-extension and forearm rotation (p <.05). The overall complication rate was 48%, however, most were minor and resolved without further surgery. No ulnar neuropathies were identified at follow-up after routine ulnar nerve transposition. CONCLUSIONS: Outcomes of AO type C distal humeral fractures were good with dual orthogonal plating, ulnar nerve transposition, and early motion. Additional plating may be required with distal fracture patterns or osteopenic bone.

Single-strand reconstruction of the lateral ulnar collateral ligament restores varus and posterolateral rotatory stability of the elbow.

Because of a lack of biomechanical studies of lateral elbow ligament reconstruction in the literature, the initial stability afforded by 3 different techniques of lateral ulnar collateral ligament reconstruction was evaluated in 8 cadaveric elbows. The arm was mounted in a testing apparatus, and passive flexion was performed with the arm in varus and valgus orientations. A pivot shift test was performed with the arm in the vertical orientation. An electromagnetic tracking device was used to quantify motion pathways. After intact testing, each specimen underwent sectioning of the radial collateral and lateral ulnar collateral ligaments from the lateral epicondyle. Reconstruction of the lateral ulnar collateral ligament was performed in a randomized sequence, consisting of proximal single-strand, distal single-strand, and double-strand tendon grafts. Division of the radial collateral and lateral ulnar collateral ligaments from the lateral epicondyle caused a significant decrease in rotational stability when the pivot shift test was being performed (P <.0001). Varus-valgus stability also decreased after transection of the radial collateral and lateral ulnar collateral ligaments (P <.0001). Reconstruction of the lateral ulnar collateral ligament restored elbow stability to that of the intact state. There was no significant difference in stability between the single- and double-strand repair techniques (P >.05). This study demonstrates that both single- and double-strand reconstructions restore varus and posterolateral elbow stability and may be considered appropriate reconstructive procedures in patients with symptomatic insufficiency of the lateral ligaments of the elbow.